1. Field of the Invention
The present invention relates to a sealing device of fluid machinery having a stationary member, an orbiting member, an end surface of which slides on an inner face of the stationary member, and a sealing member to be fitted into a sealing groove engraved on the end surface along the ridge line of the end surface, a sliding contact surface of the sealing member being pressed onto an inner surface of the stationary member with a predetermined force to slide on the inner surface in order that fluid sealing is secured between the sliding contact surface of the sealing member and the inner surface of the stationary member.
2. Description of the Related Art
In the fluid machinery such as scroll type compressors, scroll type vacuum pumps and the like, volumetric efficiencies thereof vary greatly depending on a sealing function of a working fluid between an end plate of the stationary scroll and an end surface of an orbiting scroll provided so as to revolve against the stationary scroll. Consequently, many technologies have been proposed regarding a tip seal construction between the end plate of the stationary scroll and the end surface of the orbiting scroll.
Generally, in the tip seal construction of the scroll type fluid machinery, a fluid seal between the end plate of the stationary scroll and the end surface of the orbiting scroll is secured by a construction that a sealing groove is engraved on the end surface along the ridge line of the end surface, for receiving a tip seal member fitted into the sealing groove, a sliding contact surface of the tip seal member is pressed onto an inner surface of the end plate of the stationary scroll with a predetermined force to slide on the inner surface of the end plate of the stationary scroll at the sliding contact surface.
FIG. 4 is a perspective view of an orbiting scroll of the scroll type fluid machine. In FIG. 4, the reference numeral 1 shows an orbiting scroll which moves on an inner surface of an end plate 7 (See FIG. 5) of a stationary scroll (not shown). Here, a lap 6 of a spiral wall shape is set-up on a base plate 6a of the orbiting scroll 1. Further, a sealing groove 10 is engraved on the wall end surface, namely, an end surface of the lap 6 along the ridge line of the end surface of the orbiting scroll 1, and a tip seal member 2 is fitted into the sealing groove 10.
FIG. 5 shows an example of conventional tip seal construction of the above described orbiting scroll 1. In the figure, reference numeral 6 shows a lap of the orbiting scroll 1, 7 is an end plate composing the stationary member, and 10 a sealing groove engraved on the end surface of the lap 6 along the ridge line of the tip end surface of the orbiting scroll 1. The numeral 02s shows a tip seal assembly to be fitted into the sealing groove 10, and the assembly is composed of a tip seal member 02 and a back-up ring 05. A sliding contact surface 08 of an end surface of the tip seal member 02 slides on the end plate 7, and the back-up ring 05 is made of spring materials and placed inside the tip seal member 02.
While the tip seal member 02 contacts an outer surface 05a of the back-up ring 05, the sliding contact surface 08 is pressed onto the inner surface of the end plate 7 by a spring force of the back-up ring 05 and a pressure force of fluid introduced into a clearance 9 inside the back-up ring 05. Thus, fluid sealing is secured between the sliding contact surface 08 of the tip seal 02 and the inner surface of the end plate 7.
Moreover, patent literature 1 (JP: 1998-214977,A) discloses a tip sealing construction having a stationary scroll, an orbiting scroll moving along the inner surface of an end plate of the stationary scroll, and a sealing member to be fitted into a sealing groove engraved on the end surface along the ridge line of the end surface, a sliding contact surface of the sealing member being pressed onto an inner surface of the end plate with a predetermined force to slide on the inner surface in order that fluid sealing is secured between the sliding contact surface of the tip sealing member and the inner surface of the end plate.
Further, in this disclosure, the tip seal member is formed by fitting a back-up member, which is a spring member having a C-shaped cross section, into an outer seal of C-shape cross section which contacts to slide on the inner surface of an end plate, and further fitting an O-ring inside the back-up member, thereby the elasticity of the O-ring and the back-up member of C-shape cross section presses the outer seal onto the inner surface of the end plate with a predetermined force, while the contact surfaces slide each other.
On the other hand, patent literature 2 (JP: 2001-248576,A) discloses a tip sealing construction of the scroll type fluid machinery, which is structured such that a seal member is fitted into a sealing groove provided to a lap so as to contact and slide on the inner surface of the end plate, and a rubber back-up ring of hollow circular cross section is placed between the tip seal member and a bottom face of the sealing groove, thereby the elasticity of the back-up ring presses the tip seal member onto the inner surface of the end plate.
In scroll type machinery, lap of the orbiting scroll is heated up during operation. On the other hand, in the conventional art of FIG. 5, the back-up ring 05 contacting the inner surface of the tip seal member via an outer surface 05a directly touches the lap 6 of high temperature during operation. Thus, the back-up ring 05 is heated up and deteriorated due to thermal degradation. As a result, the durability of the back-up ring 05 is lessened.
The back-up function of securing fluid sealing the sliding contact surface 08 of the tip seal member 02 and the inner surface of the end plate 7 by pressing the tip seal member 02 onto the inner surface of the end plate 7 is lowered, resulting in a lowered sealing function of working fluid as well as lowered volumetric efficiencies of fluid machinery.
In addition, in the seal construction of patent literature 1 (JP: 1998-214977,A), the tip seal member is formed by fitting a back-up member, which is a spring member having a C-shaped cross section, into an outer seal of C-shape cross section which contacts to slide on the inner surface of an end plate, and further fitting an O-ring inside the back-up member, thereby the elasticity of the O-ring and the back-up member of C-shape cross section presses the outer seal onto the inner surface of the end plate with a predetermined force, to slide on the contact surface. Therefore, the outer peripheral surface of the outer seal of C-shape cross section is pressed onto the inner surface of the end plate, substantially under a condition of line contact, so that the contact pressure in the contact part becomes high and deteriorates the durability of the outer seal and the contact surface of the outer seal is worn out. Thus the seal function between the outer seal and the inner surface of the end plate is lowered, and the volumetric efficiency of the fluid machine is decreased.
Further, because the tip seal member is structured such that a back-up member, which is a spring member having a C-shaped cross section, is fitted inside of an outer seal of C-shape cross section which and an O-ring is fitted inside the back-up member, thereby the elasticity of the O-ring and the back-up member of C-shape cross section presses the outer seal onto the inner surface of the end plate with a predetermined force, to slide on the contact surface, the seal construction is complicated, bringing difficulties such as increased man-hours as to assembling/disassembling the tip seal member.
In the construction of patent literature 2 (JP: 2001-248576,A), it is true that the tip seal member is pressed onto and slides on the inner surface of the end plate with a stable thrust force due to the elasticity of the back-up ring of hollow circular cross section, but the problem of overheating of the back-up ring remains as in the case of the above-mentioned patent literature 1 because the back-up ring made from rubber directly contacts the sealing groove of the lap.